Trig, you must be a Tach salesman.

I have broken in more engines that I care to think about, and I used a tach for the first time last summer. The only reason I bought/used it, is that I was doing an engine review, and I wanted a picture showing the tach reading. And that is still the only thing I would ever need to use one for.

What difference does it make what RPM you're turning? Use a break in prop, and set it a little on the rich side. I have broken in every engine I own this way, and every one runs beautifully.